Method of treating sized paper stock



Jan. 2, 1945.

v. L. sHAw METHOD OF TREATING SIZED PAPERL STOCK Fild Aug. s, 1940 xkuwwwk TM @Megzfom Patented Jan. 2, 1945 UNITED OFFICE METHOD OF TREATING SIZED PAPER STOCK Van L. Shaw, Chicago, 111. Application August 3, 1940,Serial No. 359,956

4 -Claims.

flhis invention relates to the drying of paper subsequent to sizingtreatment.- One object of the invention is to expedite and improve the'penetration of the sizing material into "the fiber of the paper.Another-object.is to'deliv'er the sized paper stock to the dryer at ahigh temperature to accomplish a more rapid drying action therein. Andit is also an object to secure an improved quality in the surface of thepaper as a result of the sizing and drying operation when conducted inaccordance with this invention. The invention consists in certainfeatures and elements of the apparatusiand in certain steps of theprocess herein described and illustrated in V the drawing, as indicatedby the claims.

In the drawing:

, Figure 1 is a diagrammatic side elevation with to be evaporated fromthe surface of the paper.

before it has properly penetrated the body of the fiber, and before ithas become uniformly distributed. The evaporation cools the sizingmixture, increasing its viscosity and retarding or arresting penetrationand distribution into the fbody' of the paper. As a result,.the sizingoperation is imperfectly performed, and in the case of sizing which'tends to produce a cockle surface the pattern is likely to be quitecoarse and l rather uneven. The present invention inte'rposes betweenthe sizing tub and the dryer a substantially closed chamber throughwhich the sized stock travels directly from the sizing tub, and in whicha relatively high temperature is maintained. Preferably, the paper isexposed in this chamber to radiant heat. which has the effect ofkeepingthe sizing in fluid condition during the movement of the paperthrough the chamber, and thus affording more time and a betteropportunity for the sizing to penetrate the fiber and distribute itselfwith uniformity over the entire area of the paper. I

Figure 1 illustrates diagrammatically an apparatus adapted to performthese related steps in accordance with the invention, and indicates asupply reel of paper at A, with the paper web P feeding overan idlerroll B and thence into the sizing tub C in which the paper is guidedover a roll D,'and from which it emerges to pass between the rolls D andE, and thence into the closed treating chamber which is characteristicof this invention. The enclosure F may be unextending to the floor andto the ceiling, or pro 'vided with a top wall G, as shown. Portions ofthe side walls may bemade removable or hinged for convenience of accessto the apparatus within the chamber, but, normally, during operationthereof they will be kept closed. web enters near the top of the chamberthrough a small opening H and passes over guide rollers .1 near the topof the chamber, and cooperating rollers K near the bottom, which guidethe paper alternately downward and upward as it progressesthrough thechamber F. Between the vertically extending portions of the web P. thereare mounted fixed radiator sections M which may be of any convenientdesign or type to provide radiant heat directed against the exposed,surface 20 of'the paper web as it travels pastthem. For purposes ofillustration the radiator units M may be understood as heated by steam,and, as indicated in Figure 2, each section M is shownas consisting ofheaders M and M connected by" 2:; horizontal tubes M An inlet pipe N isconnected to the upper portion of the header M and a partition 1w insaid header at about the middle of its height forces the steam to travelhorizontally through the upper tubes M and to the header M, and toreturn through the lower tubes M into the lower half of the header Mwhich is" connected to the outlet pipe 0. The several inlet pipes N areconnected to a common supply pipe Q, and, if desired, this passage maybe fitted with a thermostatically controlled supply 'valve R with athermally responsive element shown at S, within the chamber F, tomaintain a substantially uniform temperature therein.

The rolls J and K are indicated only 40 matieally in the drawing, but itmay be understood that they may be of substantially the same design asthe rolls of a. standarddryer in which thepaper web is thus fed back andforth while its excess moisture is being evaporated. But inthe chamber Fsubstantially no evaporation takes place because the humidity ofthechamber is maintained fairly close to the saturation point. Thus,although suflicient heat is supplied by the radiators M to produce andmaintain a tempera 5o ture of about 200 F., within thechamber F, the

sizing solution which has been applied to the; paper web P in the tubCwill not dry while the paper web is passing through the chamber F;

The usual temperature of the size tub is from 66 129 to F., and thefurther heating of the.

derstood as including vertical walls on four sides,

The paper.

diagramsizing solution as it is carried on the paper Web into thechamber F maintains it in thoroughly fluid condition, and, at the same,time, causes it to penetrate more deeply into the fiberof the paperstock and to distribute itself more uniformly.

Through a small opening T the paper web emerges from the chamber F andtravels over idler rolls U and V onto the rolls of a typical dryer W.The temperature of this section will not usually exceed 150 or 160 F.,but the sensible heat of the paper emerging from the heater section atF, vat 200 F..or more, acts to increase the temperature of the air inthe immediate vicinity of the paper web as it travels over the dryer andincreases the capacity of this air to absorb moisture, thus hasteningthe evaporation of the moisture fromthe paper itself,- In some cases ithas been found that the eificiency of the dryer is increased as much astwenty percent by the addition of the chamber F with its radiant heaterunits M installed in accordance with this invention.

Whilethere is shown anddescribed herein certain specificstructureembodying the invention,

together with certain procedure, it will be manieludes passing the paperstock through a liquid sizing mixture, then subjecting it to'radlantheat of sufilcient intensity to increase its temperature and in asubstantially saturated atmosphere to prevent evaporation of the sizingmaterial during this step of the process, and finally applyingrelatively dry heated air to' the surface of the paper to absorb surplusmoisture therefrom.

2. The process of finishing paper' which includes treating the paperstock with a liquid size,

then moving the paper web through a relatively moist atmosphere andsimultaneously past a source of radiant heat suflicient-ly intense tosubstantially increase the temperature of the web a substantially closedchamber having an atmosphere of relatively high humidity and thenexposing the heated web to comparatively dry air to remove its surplusmoisture.

51. The process of finishing paper which includes treating the paperstock with a liquid

